Weather Update

Email Weather Briefing *Edited for brevity*

Courtesy:  NOAA/NWS, Portland, OR

Thursday, December 19, 2013

 

SYNOPSIS:  We are monitoring the potential for a mix of snow, sleet, and/or freezing rain across the lowlands Friday morning.  A Pacific warm front will gradually spread clouds and precipitation into the area sometime Friday morning.  Temperatures may or may not be below freezing at the time precipitation begins, leading to a significant amount of uncertainty with this event.  There is much greater certainty that temperatures will be above freezing most areas (except perhaps the Columbia Gorge) by noon Friday.  Details should come into better focus as today progresses.

 

PRIMARY AREAS IMPACTED: 

•Friday morning:  Areas Coast Range eastward, with the greatest risk being in Clark County, the Willapa Hills, the Cowlitz River Valley, and the Columbia River Gorge.  The risk of a significant event decreases south of Portland, with only a very slight chance of a significant event near Eugene.

 

IMPACTS: 

•Friday morning:  Snow and ice may impact the Friday morning commute, even within the main metro areas.  Worst case scenario for the metro areas has about 2 inches of snow and/or a tenth of an inch of ice.  Greater snow and ice accumulations are possible but not likely in the Gorge.

 

TIMING: 

•Friday morning:  Greatest risk prior to 8am, though there is some uncertainty.  Much warmer air should cause a rapid thaw for most areas around mid-morning, with the Gorge being last to thaw around midday or early Friday afternoon.

 

FORECAST CONFIDENCE: 

•Friday morning:  Low.  Timing will be everything, as precipitation will need to start before temperatures rise above freezing for snow and ice issues to occur.  Details will become clearer as today progresses.